Page 716 - Withrow and MacEwen's Small Animal Clinical Oncology, 6th Edition

694 PART IV Specific Malignancies in the Small Animal Patient

Dogs with GI lymphoma usually present with nonspecific
GI signs, such as vomiting, diarrhea, weight loss, and mal-
absorption.
Mesenteric LNs, spleen, and liver may be
61,64,125–128
VetBooks.ir involved.
The mediastinal form of lymphoma is characterized by enlarge-
ment of the cranial mediastinal structures and/or thymus (see
Fig. 33.2), and clinical signs are associated with the extent of dis-
ease with resulting respiratory compromise or polydipsia/polyuria
from hypercalcemia. In advanced cases, dogs present with respira-
tory distress caused by a space-occupying mass and pleural effu-
sion, exercise intolerance, and possibly regurgitation. In addition,
dogs with mediastinal lymphoma may have precaval syndrome,
characterized by pitting edema of the head, neck, and forelimbs
secondary to tumor compression or invasion of the cranial vena
cava (Fig. 33.5).
Clinical signs in dogs with extranodal lymphoma depend on
the specific organ involved. Cutaneous lymphoma can be muco-
cutaneous, cutaneous, or both. Lesions can be solitary, gener-
• Fig. 33.4 Lateral projection of a thoracic radiograph of a dog with diffuse alized, or multifocal. 71,74–76,129–132 Tumors occur as nodules,
interstitial infiltration with lymphoma secondary to multicentric lymphoma. plaques, ulcers, and erythemic or exfoliative dermatitis with focal

A B

C
• Fig. 33.5 (A) Facial edema in a dog with precaval syndrome secondary to mediastinal lymphoma. (B)
Forelimb edema in a dog with precaval syndrome secondary to mediastinal lymphoma. (C) The dog in
(B) 24 hours after radiation therapy to the cranial mediastinal mass, showing resolution of pitting edema.